Method of operating a direct injection spark-ignited engine with a fuel composition

ABSTRACT

The present invention is directed to a method to clean up or keep clean the fuel system of a direct injection spark-ignited engine by operating the engine with a fuel composition that includes a liquid fuel and a fuel additive composition.  
     The fuel additive composition useful in the present invention has at least one nitrogen-containing dispersant and optionally a fluidizer where the dispersant has a specific lipophilic parameter and the dispersant or the dispersant and the fluidizer have a specific hydrophilic-lipophilic parameter, the dispersant provides about 0.15 to about 50 ppm by weight nitrogen in the fuel composition, and the fluidizer and/or the dispersant provide about 10 to about 10,000 ppm by weight active components in the fuel composition.  
     The method of the present invention is effective in controlling deposits in fuel injectors and combustion chambers of a direct injection spark-ignited engine.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention involves a method of operating a directinjection spark-ignited engine (DISE) using a fuel compositioncomprising a liquid fuel and a fuel additive composition. The methodprovides for the cleanliness of the fuel system of the DISE.

[0003] 2. Description of the Related Art

[0004] The direct injection spark-ignited engine is a new technologythat has been commercially introduced in Japan and Europe bymanufacturers Mitsubishi, Nissan and Toyota. The DISE offers significantperformance benefits relative to a conventional port fuel injectiongasoline engine (PFIGE). The specific power output of a DISE relative toa PFIGE is increased, which results in better fuel economy anddriveability in terms of throttle response and acceleration. The DISE,when coupled with current catalyst systems for reducing exhaustemissions, also meets exhaust emission standards. The overallperformance of a DISE is directly related to the cleanliness of the fuelsystem. Consequently, methods that provide for the cleanliness of thefuel system of a DISE are very desirable and useful.

[0005] International publication WO 00/20537, Haji et al., publishedApr. 13, 2000, discloses a gasoline additive comprising at least onenitrogenous compound selected from a nitrogen-containing ether compoundand a polybutenylamine compound. The gasoline additive is suitable foruse in a gasoline composition for direct injection gasoline engines.

[0006] International publication WO 01/42399, Aradi et al., publishedJun. 14, 2001, discloses that deposits in a direct injection gasolineengine are reduced by fueling the engine with a fuel compositioncomprising a Mannich detergent.

[0007] A number of technical presentations involve studies done ondirect injection gasoline or spark ignition engines that genericallydisclose nitrogen-containing compounds and polyether fluidizers as fueladditives in these engines:

[0008] 1. “A Comparison of Gasoline Direct Injection and Port FuelInjection Vehicles, Part 1: Fuel System Deposits,” Arters et al., 5^(th)Annual Fuels & Lubes Asia Conference, 1999;

[0009] 2. “A Comparison of Fuel System Deposits and LubricantPerformance in Gasoline Direct Injection and Port Fuel InjectionVehicles,” Macduff et al., 2^(nd) International Fuels Colloquium, Jan.20-21, 1999;

[0010] 3. “A Comparison of Gasoline Direct Injection and Port FuelInjection Vehicles; Part 1-Fuel System Deposits and VehiclePerformance,” Arters et al., SAE Paper No. 1999-01-1498 presented atInternational Spring Fuels and Lubricants Meeting and Exposition, May3-6, 1999;

[0011] 4. “A Study of Fuel Additives for Direct Injection Gasoline (DIG)Injector Deposit Control,” Aradi et al., SAE, Spec. Publ., VSP-1551,Diesel and Gasoline Performance and Additives, p283-293;

[0012] 5. “Deposit Formation and Control in Direct Injection SparkIgnition Engines,” Ohkubo et al., 6^(th) Annual Fuels & Lubes AsiaConference, Jan. 25-28, 2000;

[0013] 6. “The Effect on Vehicle Performance of Injector Deposits in aDirect Injection Gasoline Engine,” Arters et al., SAE Paper No.2000-01-2021.

[0014] Japanese Patent Publication JP 11-35952, Nippon Oil Company,published Feb. 9, 1999, discloses an alcoholic compound as a gasolineadditive for in-cylinder direct injection type gasoline engines.

[0015] The method of the present invention effectively provides for thecleanliness of a fuel system of a DISE by operating the engine with afuel composition comprising a liquid fuel and a fuel additivecomposition. The present invention controls deposits in fuel injectorsand combustion chambers of a DISE that contributes to vehicleperformance in the areas of fuel economy, driveability and exhaustemissions.

SUMMARY OF THE INVENTION

[0016] An object of the present invention is to provide for thecleanliness of the fuel system of a direct injection spark-ignitedengine.

[0017] A further object of the present invention is to provide for thecleanliness of the fuel injectors and combustion chambers of a directinjection spark-ignited engine.

[0018] Additional objects and advantages of the present invention willbe set forth in part in the description that follows and in part will beobvious from the description or may be learned by the practice of thisinvention. The objects and advantages of this invention may be realizedand attained by means of the instrumentalities pointed out in theappended claims.

[0019] To achieve the foregoing objects in accordance with theinvention, as described and claimed herein, the method of the presentinvention to clean up or keep clean a fuel system of a direct injectionspark-ignited engine comprises operating the engine with a fuelcomposition comprising a liquid fuel; and a fuel additive compositioncomprising at least one nitrogen-containing dispersant; and optionally afluidizer, wherein a molecular volume factor for the dispersant is about50 or greater, a modified hydrophilic lipophilic balance (HLBm) valuefor the dispersant or for the dispersant and the fluidizer is greaterthan about zero, the concentration of nitrogen in the fuel compositionfrom the dispersant is about 0.15 to about 50 ppm by weight, and theconcentration of active components in the fuel composition from thedispersant or the dispersant and the fluidizer is about 10 to about10,000 ppm by weight.

[0020] In another instance of the method of the present invention, theliquid fuel is selected from the group consisting of a hydrocarbonaceousfuel, a non-hydrocarbonaceous fuel, and mixtures thereof.

[0021] In another embodiment of the method of the present invention, thenitrogen-containing dispersant is selected from the group consisting ofa polyetheramine; a Mannich reaction product of ahydrocarbyl-substituted phenol, an aldehyde, and an amine; ahydrocarbyl-substituted succinimide; a hydrocarbylamine; and mixturesthereof.

[0022] In a further embodiment of the method of the present invention,the fluidizer is a polyether represented by the formulaR⁷O[CH₂CH(R⁸)O]_(q)H wherein R⁷ is a hydrocarbyl group; R⁸ is selectedfrom the group consisting of hydrogen, hydrocarbyl groups of 1 to 16carbon atoms, and mixtures thereof; and q is a number from 2 to about50.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention involves a method to clean up or keep cleana fuel system of a direct injection spark-ignited engine (DISE). Themethod achieves this cleanliness by controlling deposits in the fuelsystem in a dual action of cleaning up or removing deposits that haveformed and keeping clean or preventing deposits from forming.Introduction of the fuel additive composition via the fuel compositioninto a DISE having a dirty or deposit-containing fuel system cleans upthe fuel system by removing deposits that have formed. Introduction ofthe fuel additive composition via the fuel composition into a DISEhaving a clean fuel system keeps the fuel system clean by preventingdeposits from forming.

[0024] The fuel system in a DISE includes as components the intakevalves, fuel injectors, spark plugs, combustion chambers and exhaustvalves. Cleanliness of the fuel system provided by the method of thepresent invention is determined by measuring the amount of deposits or aproperty directly related to deposits for those components that have asignificant effect on vehicle performance, which include fuel injectorsand combustion chambers. Cleanliness of the fuel system provided by themethod of the present invention can be determined as a do no harm tovehicle performance of this DISE technology for those components forwhich the liquid fuel and the fuel additive composition normally have anegligible or minor effect on in terms of deposits, which include intakevalves, exhaust valves and spark plugs.

[0025] Vehicle performance is determined by measuring for fuel economy,driveability and exhaust emissions. Driveability includes throttleresponse, as misfires or stalls, and acceleration. Exhaust emissionsinclude levels of the regulated species hydrocarbons, carbon monoxideand nitrogen oxides. Although not now regulated, levels of particulatescan be included under exhaust emissions.

[0026] The fuel composition of the present invention comprises a liquidfuel and a fuel additive composition. The fuel composition is usuallyprepared by adding the fuel additive composition to the liquid fuel andmixing them at ambient temperature until the resultant fuel compositionis homogeneous.

[0027] The liquid fuel of the present invention can be selected from thegroup consisting of a hydrocarbonaceous fuel, a non-hydrocarbonaceousfuel, and mixtures thereof. Hydrocarbonaceous fuels are normallyhydrocarbon petroleum distillates such as gasoline as defined by ASTMspecification D4814 for a mixture of hydrocarbons having a distillationrange per ASTM procedure D86 from about 60° C. at the 10% distillationpoint to about 205° C. at the 90% distillation point. Hydrocarbonaceousfuels can also be derived from the mineral resources of shale and coal.Non-hydrocarbonaceous materials or fuels can be oxygen-containingcompounds also known as oxygenates which include alcohols, ethers,organo-nitro compounds and esters of fatty carboxylic acids, forexample, methanol, ethanol, diethyl ether, methyl ethyl ether, methylt-butyl ether, nitromethane, and esters from vegetable oils. Thenon-hydrocarbonaceous fuels can be obtained from both mineral andvegetable sources. The liquid fuel can be a mixture of two or morehydrocarbonaceous fuels, of two or more non-hydrocarbonaceous fuels, orof one or more hydrocarbonaceous fuels and one or morenon-hydrocarbonaceous fuels. An example of such mixtures is thecombination of gasoline and ethanol.

[0028] The fuel additive composition of the present invention comprisesat least one nitrogen-containing dispersant. The nitrogen-containingdispersant can be selected from the group consisting of apolyetheramine; a Mannich reaction product of a hydrocarbyl-substitutedphenol, an aldehyde, and an amine; a hydrocarbyl-substitutedsuccinimide; a hydrocarbylamine and mixtures thereof.

[0029] The term hydrocarbyl throughout this specification and theappended claims is a univalent radical of one or more carbon atoms thatis predominately hydrocarbon in nature, but can have non-hydrocarbonsubstituent groups and can include heteroatoms.

[0030] The polyetheramine of the present invention can be represented bythe formula R[OCH₂CH(R¹)]_(n)A wherein R is a hydrocarbyl group, R¹ isselected from the group consisting of hydrogen, hydrocarbyl groups of 1to 16 carbon atoms, and mixtures thereof; n is a number from 2 to about50; and A is selected from the group consisting of —OCH₂CH₂CH₂NR²R² and—NR³R³ wherein each R² is independently hydrogen or hydrocarbyl; andeach R³ is independently hydrogen, hydrocarbyl or —[R⁴N(R⁵)]_(p)R⁶wherein R⁴ is C₂-C₁₀ alkylene, R⁵ and R⁶ are independently hydrogen orhydrocarbyl; and p is a number from 1-7.

[0031] The polyetheramine of the present invention can be prepared byinitially condensing an alcohol or alkylphenol with an alkylene oxide,mixture of alkylene oxides or with several alkylene oxides in sequentialfashion in a 1:2-50 mole ratio of hydric compound to alkylene oxide toform a polyether intermediate.

[0032] The alcohol can be linear or branched from 1 to 30 carbon atoms,or in another instance from 6 to 20 carbon atoms, or alternatively from10 to 16 carbon atoms. The alkyl group of the alkylphenol can be 1 to 30carbon atoms, or alternatively 10 to 20 carbon atoms.

[0033] The alkylene oxide can be ethylene oxide, propylene oxide orbutylene oxide. The number of alkylene oxide units in the polyetherintermediate can be 10-35, or in another instance 18-27.

[0034] U.S. Pat. No. 5,094,667 provides reaction conditions forpreparing a polyether intermediate, the disclosure of which isincorporated herein by reference.

[0035] The polyether intermediate can be converted to a polyetheramineby amination with ammonia, an amine or a polyamine to form apolyetheramine of the type where A is —NR³R³. European Patent EP310875provides reaction conditions for the amination reaction, the disclosureof which is incorporated herein by reference. Polyetheramines of thetype where A is —NR³R³ are commercially available as the Jeffamine®series from Huntsman. Alternately, the polyether intermediate can beconverted to a polyetheramine of the type where A is —OCH₂CH₂CH₂NH₂ byreaction with acrylonitrile followed by hydrogenation. U.S. Pat. No.5,094,667 provides reaction conditions for the cyanoethylation withacrylonitrile and subsequent hydrogenation, the disclosure of which isincorporated herein by reference. U.S. Pat. No. 5,830,243 discussesmethods of preparing polyetheramines, the disclosure of which isincorporated herein by reference.

[0036] The Mannich reaction product of the present invention is preparedfrom a hydrocarbyl-substituted phenol. The hydrocarbyl substituent canhave a number average molecular weight of 500 to 3000, or alternatively700 to 2300, or in another instance 750 to 1500. The hydrocarbylsubstituent is generally derived from a polyolefin. The polyolefin isgenerally derived from the polymerization of an olefin monomer includingethylene, propylene, various butene isomers such as isobutylene, andmixtures thereof. The hydrocarbyl-substituted phenol can be obtained byalkylating phenol with a polyolefin using an alkylation catalyst such asboron trifluoride. Polyisobutylenes can be used to alkylate phenol, andhighly reactive polyisobutylene can be used in the alkylation in whichat least 70% of the olefinic double bonds in the polyisobutylene are ofthe vinylidene type at a terminal position on the polymer chain. Acommercial example of highly reactive or high vinylidenepolyisobutylenes is Glissopal® marketed by BASF.

[0037] The aldehyde used to prepare the Mannich reaction product of thepresent invention can be a C₁-C₆ aldehyde. Formaldehyde can be used inone of its reagent forms such as paraformaldehyde and formalin.

[0038] The amine used to prepare the Mannich reaction product of thepresent invention can be a monoamine or a polyamine and includes organiccompounds containing at least one HN< group suitable for use in theMannich reaction. Polyamines include dimethylaminopropylamine,alkylenepolyamines such as ethylenediamine and polyalkylenepolyaminessuch as diethylenetriamine.

[0039] The conditions required for the Mannich reaction to form theMannich reaction product of this invention are known in the art. Fortypical conditions for the Mannich reaction see U.S. Pat. No. 3,877,889;U.S. Pat. No. 5,697,988 and U.S. Pat. No. 5,876,468, the disclosures ofwhich are incorporated herein by reference.

[0040] The hydrocarbyl group of the hydrocarbyl-substituted succinimideof the present invention can be derived from a polyolefin having anumber average molecular weight of 500 to 5,000, or in another instance700 to 2,300 or alternatively 750 to 1,500. The polyolefin is generallyderived as described above for the Mannich reaction product frompolymerization of olefin monomers such as polyisobutylene frompolymerized isobutylene. The polyisobutylene can be the highly reactivetype having at least 70% of its olefinic double bonds as the vinylidenetype. The hydrocarbyl-substituted succinimide is usually prepared byreacting a hydrocarbyl-substituted succinic acylating agent with anamine having a —NH₂ group. The amine can be a polyamine to includealkylenepolyamines such as ethylenediamine and polyalkylenepolyaminessuch as tetraethylenepentamine and polyethylenepolyamine bottoms. U.S.Pat. Nos. 4,234,435 and 5,719,108 provide descriptions of methods toprepare hydrocarbyl-substituted succinimides, the disclosures of whichare incorporated herein by reference.

[0041] The hydrocarbylamine of the present invention can be derived froma polyolefin having a number average molecular weight of 500 to 5000, oralternatively 700 to 2300, or in another instance 750 to 1500. Thehydrocarbylamine can be prepared by chlorinating a polyolefin and thenreacting the chlorinated polyolefin with an amine or an alkanolamine inthe presence of a base such as sodium carbonate or sodium hydroxide. Thepolyolefin can be polyisobutylene. The amine can be a polyamine toinclude alkylenepolyamines such as ethylenediamine andpolyalkylenepolyamines such as diethylenetriamine. The alkanolamine canbe a polyamine such as aminoethylethanolamine. U.S. Pat. No. 5,407,453describes a method to prepare hydrocarbylamines, the disclosure of whichis incorporated herein by reference.

[0042] The fuel additive composition of the present invention comprisesoptionally a fluidizer. The fluidizer can be a polyether represented bythe formula R⁷O[CH₂CH(R⁸)O]_(q)H wherein R⁷ is a hydrocarbyl group; R⁸is selected from the group consisting of hydrogen, hydrocarbyl groups of1 to 16 carbon atoms, and mixtures thereof; and q is a number from 2 toabout 50. Embodiments and a method of preparation for the polyether werepresented above in the description of the polyetheramine under thedescription of the polyether intermediate. A commercial example of thepolyether is the Bayer Actaclear® series. Commercial samples are alsoavailable from Dow Chemical Co., Huntsman, and ICI.

[0043] The method of the present invention comprises operating a directinjection spark-ignited engine with a fuel composition that comprises aliquid fuel and a fuel additive composition comprising at least onenitrogen-containing dispersant and optionally a fluidizer wherein, asdescribed herein, a molecular volume factor for the dispersant is about50 or greater, a modified hydrophilic lipophilic balance (HLBm) valuefor the dispersant or for the dispersant and fluidizer is greater thanabout zero, the concentration of nitrogen in the fuel composition fromthe dispersant is about 0.15 to about 50 ppm by weight, and theconcentration of active components in the fuel composition from thedispersant or the dispersant and the fluidizer is about 10 to about10,000 ppm by weight. The concentration of the dispersant or thedispersant and fluidizer given in ppm by weight throughout thisapplication, unless indicated otherwise, is based on active componentsand does not include diluents such as hydrocarbon solvents.

[0044] In another embodiment of the method of the present invention, theHLBm value for the dispersant or for the dispersant and the fluidizer isgreater than about 50, the concentration of nitrogen in the fuelcomposition from the dispersant is about 0.20 to about 25 ppm by weight,and the concentration of the active components in the fuel compositionfrom the dispersant or the dispersant and the fluidizer is about 20 toabout 4,000 ppm by weight.

[0045] In a further embodiment of the method of the present invention,the HLBm value for the dispersant or for the dispersant and thefluidizer is greater than about 100, the concentration of nitrogen inthe fuel composition from the dispersant is about 0.25 to about 15 ppmby weight, and the concentration of the active components in the fuelcomposition from the dispersant or the dispersant and the fluidizer isabout 30 to about 3,200 ppm by weight.

[0046] To practice the method of the present invention, the fuelcomposition needs to simultaneously satisfy four requirements which area minimum molecular volume factor, a modified hydrophilic lipophilicbalance value, a nitrogen concentration and an active componentsconcentration for the dispersant or for the dispersant and the fluidizeras indicated in the embodiments of the invention described above. Inturn the fuel additive composition needs to be formulated so that thesefour requirements are met. The fuel additive composition can beformulated to meet these requirements by selecting at least onenitrogen-containing dispersant, and optionally a fluidizer such as apolyether. The nitrogen-containing dispersant can be selected from thegroup consisting of a polyetheramine, a Mannich reaction product, asuccinimide, a hydrocarbylamine, and mixtures thereof. Examples offormulations for the fuel additive composition capable of meeting theabove described requirements are the following: a polyetheramine andoptionally a fluidizer, a Mannich reaction product and optionally afluidizer, a succinimide and optionally a fluidizer, a hydrocarbylamineand optionally a fluidizer, a polyetheramine and a Mannich reactionproduct and optionally a fluidizer, a polyetheramine and a succinimideand optionally a fluidizer, a polyetheramine and a hydrocarbylamine andoptionally a fluidizer, a Mannich reaction product and a succinimide andoptionally a fluidizer, a Mannich reaction product and ahydrocarbylamine and optionally a fluidizer, and a succinimide and ahydrocarbylamine and optionally a fluidizer. Formulations for the fueladditive composition capable of meeting the four requirements are alsopossible by selecting combinations of three or four members from thenitrogen-containing dispersant group consisting of a polyetheramine, aMannich reaction product, a succinimide, and a hydrocarbylamine, andoptionally a fluidizer such as a polyether.

[0047] The four requirements regarding the fuel additive composition inthe fuel composition of molecular volume factor, modified hydrophiliclipophilic balance value, nitrogen concentration and active componentsconcentration correspond with the dispersant or the dispersant andfluidizer being soluble in the liquid fuel and effective in controllingdeposits in the fuel system. Hydrophilic lipophilic balance (HLB) valuescan be calculated as a function of molecular volume and water ofsolvation as described by John C. McGowan in “A New Approach for theCalculation of HLB Values of Surfactants,” Tenside Surf. Det. 27 (1990)4, pp. 229-230 via the formula HLB=7−(0.337)(10⁵)(Vx)+(1.5)(n). HLBvalues calculated by this method were found to have a statisticallysignificant correlation with combined combustion chamber and fuelinjector deposit performance in a direct injection spark-ignited engine,however, modified hydrophilic lipophilic balance values were found tohave superior correlation with the combined deposit performance asdemonstrated in the examples herein below. The HLBm values can becalculated by a modification, which emphasizes the hydrophilic property,of the formula used to calculate HLB values which is

HLBm=7−(0.337)(10⁵)(Vx)+(7.5)(n).

[0048] The molecular volume factor (10⁵)(Vx) for a dispersant orfluidizer molecule is related to the lipophilic nature of that moleculeand directly related to its molecular weight. The molecular volumefactor for a given molecule can be determined by first multiplying anatomic volume value by the total number of atoms for each atomic elementpresent in the molecule to give products which are total atomic volumes,second summing these total atomic volumes, and lastly subtracting fromthis summation an adjustment due to bonding which is the product of(0.656)(total number of bonds in the molecule) where all bonds includingdouble and triple bonds are counted as single bonds. The atomic volumevalues for atoms in this application are as follows: 0.871 for H, 1.635for C, 1.243 for O and 1.439 for N.

[0049] The water of solvation factor n is the number of water moleculesthat can be involved in solvation of a dispersant or fluidizer moleculeand is related to the hydrophilic nature of that molecule. Water ofsalvation values for heteroatom types in this application are asfollows: 1 for oxygen and 1 for nitrogen except that a primary aminenitrogen such as the nitrogen in methylamine has a value of 2. The waterof salvation factor for a given molecule is obtained by summing theproducts of (water of salvation value for a heteroatom type) times(total number of a heteroatom type in the molecule) for each heteroatomtype present in the molecule.

[0050] The modified HLB value for a given dispersant or fluidizermolecule is then determined by entering the calculated values for themolecular volume factor (10⁵)(Vx) and the water of solvation factor ninto the formula HLBm=7−(0.337)(10⁵)(Vx)+(7.5)(n).

[0051] When there are 2 or more dispersant or dispersant and fluidizermolecules present in the fuel additive composition, the HLBm value fortheir combination is determined by first calculating the HLBm value foreach different molecule as described above. The HLBm value for theircombination is then determined by summing the products of the weightfraction and the HLBm value for each different dispersant and fluidizermolecule present. The weight fraction for a dispersant or fluidizermolecule can be determined from the ratio of the weight of that moleculeto the total weight of all the dispersant and fluidizer moleculespresent in the fuel additive composition.

[0052] Illustrative of the method to calculate modified HBLB values, thecalculation of the HLBm value for ethanol is outlined as follows. Themolecular volume factor for ethanol having 6-Hs, 2-Cs, 1-O and 8 bondsis 4.491. The water of solvation factor for ethanol with one oxygenheteroatom is 1. The HLBm value for ethanol is[7−(0.337)(4.491)+(7.5)(1)] or 13.

[0053] The embodiments of the present invention provide ppm weightranges for the concentration of nitrogen and for the concentration ofactive components in the fuel composition from the dispersant or thedispersant and fluidizer that provide for effective control of depositsin the fuel system by the method of the present invention whether thefuel composition is the result of additive treatment of the liquid fuelat a fuel terminal or an aftermarket additive treatment.

[0054] The fuel compositon and fuel additive composition of the presentinvention can contain a hydrocarbon solvent to provide for compatibilityor homogeneity and in the fuel additive composition to facilitatehandling and transfer. The hydrocarbon solvent concentration in the fueladditive composition can be 10-80% by weight, alternatively 20-70% byweight, and in another instance 30-60% by weight. The hydrocarbonsolvent can be an aliphatic fraction, aromatic fraction, or mixture ofaliphatic and aromatic fractions where the flash point is generallyabout 40° C. or higher. The hydrocarbon solvent is typically an aromaticnaphtha having a flash point above 62° C. or an aromatic naphtha havinga flash point of 40° C. or a kerosene with a 16% aromatic content havinga flash point above 62° C.

[0055] The fuel additive composition and fuel composition of the presentinvention can contain other additives that are well known to those ofskill in the art. These can include anti-knock agents such astetra-alkyl lead compounds and MMT (methylcyclopentadienyl manganesetricarbonyl), lead scavengers such as halo-alkanes, dyes, antioxidantssuch as hindered phenols, rust inhibitors such as alkylated succinicacids and anhydrides and derivatives thereof, bacteriostatic agents,auxiliary dispersants and detergents, gum inhibitors, fluidizer oils,metal deactivators, demulsifiers, anti-valve seat recession additivessuch as alkali metal sulphosuccinate salts, and anti-icing agents. Thefuel composition of this invention can be a lead-containing or lead-freefuel, typically a lead-free fuel.

[0056] The following examples are illustrative of the method of thepresent invention to clean up or keep clean the fuel system of a directinjection spark-ignited engine by controlling deposits, but are notlimiting on the scope of the invention as defined by the appendedclaims.

[0057] Examples 1-16 demonstrate the effectiveness of the method of thepresent invention in controlling deposits in the combustion chambers andfuel injectors of a direct injection spark-ignited engine in real world,vehicle tests. This controlling of deposits in the combustion chambersand fuel injectors is directly correlated to vehicle performance.Excellent control of one deposit type does not insure control of theother. The present invention provides a method to optimize performancefor both injector and combustion chamber deposits in DISE engines. Thegreater the HLBm value for the nitrogen-containing dispersant andfluidizer when present, the greater the assurance that both injector andcombustion chamber deposit control will be achieved provided the otherthree requirements of molecular volume factor, nitrogen concentrationand actives concentration are met. TABLE I Vehicle Keep Clean FieldTest¹ Avg Inj Example Fuel Treated HLBm Average CCD³ Flow Loss⁴ 1 No —9.2 3.2% 2 PIBEDA/PE-1² 71 8.8 −0.1% # of nitrogen, and theconcentration of hydrocarbylamine and polyether in the treated fuel was425 ppm by weight on an actives basis.

[0058] TABLE II Vehicle Keep Clean Field Test¹ Ex- ample Fuel TreatedHLBm Average CCD⁴ Avg Inj Flow Loss⁵ 3 No — 16.0 2.9% 4 Mannich/PE-2² 48 16.6 1.3% 5 PEA³ 129 13.8 1.0% # nitrogen and was 335 ppm by weighton an actives basis.

[0059] TABLE III Vehicle Keep Clean Field Test¹ Example Fuel TreatedHLBm Average CCD⁴ 6 No — 0.94 7 Mannich/PE-2² 48 0.95 8 PIBEDA/Oil³ −71.41

[0060] TABLE IV Vehicle Fuel Injector Deposit Keep Clean Tests¹ Ex-ample Fuel Treated HLBm Avg. Flow Loss⁴ Max Flow Loss⁵  9 No — 17.9%33.4% 10 Mannich/PE-2² 48 3.4% 11.3% 11 Mannich/PE-1³ 81 4.2% 6.9%

[0061] TABLE V Vehicle Fuel Injector Deposit Clean Up Tests¹ Test Rateof Example Fuel Treated HLBm Duration Avg. Clean Up⁵ Clean Up 12Mannich/PE-1² 81 8,000 km 4.9% 0.61 × 10⁻³%/km 13 PEA³ 129  5,000 km3.5% 0.70 × 10⁻³%/km 14 Succinimide/Oil⁴ 16 5,000 km 4.3% 0.86 ×10⁻³%/km # (EOT) but the engine was not disassembled. Example 12 was runfor 8,000 km followed by Example 13 for 5,000 km and finally Example 14for 5,000 km.

[0062] TABLE VI Vehicle CCD Clean Up Field Test Avg CCD Thickness CCDClean Example Fuel Treated HLBm SOT EOT Up³ 15¹ PEA 129 16.6  8.8 47%16² Mannich/PE-1  81 19.1 16.7 12% # intake valve deposits, which arenot directly impacted by additive in DISE engines under normaldosages/operating modes, were reduced by 23% by this treatment. # andwas 3200 ppm by weight on an actives basis. Intake valve deposits werealso reduced, by 28%, by this treatment.

What is claimed is:
 1. A method to clean up or keep clean a fuel systemof a direct injection spark-ignited engine, comprising: operating theengine with a fuel composition comprising a liquid fuel; and a fueladditive composition comprising at least one nitrogen-containingdispersant; and optionally a fluidizer, wherein a molecular volumefactor for the dispersant is about 50 or greater, a modified hydrophiliclipophilic balance (HLBm) value for the dispersant or for the dispersantand the fluidizer is greater than about zero, the concentration ofnitrogen in the fuel composition from the dispersant is about 0.15 toabout 50 ppm by weight, and the concentration of active components inthe fuel composition from the dispersant or the dispersant and thefluidizer is about 10 to about 10,000 ppm by weight.
 2. The method ofclaim 1, wherein the liquid fuel is selected from the group consistingof a hydrocarbonaceous fuel, a non-hydrocarbonaceous fuel, and mixturesthereof.
 3. The method of claim 2, wherein the liquid fuel is selectedfrom the group consisting of gasoline, ethanol, and mixtures thereof. 4.The method of claim 1, wherein the HLBm value is greater than about 50,the concentration of the nitrogen is about 0.20 to about 25 ppm byweight, and the concentration of the active components is about 20 toabout 4,000 ppm by weight.
 5. The method of claim 1, wherein the HLBmvalue is greater than about 100, the concentration of the nitrogen isabout 0.25 to about 15 ppm by weight, and the concentration of theactive components is about 30 to about 3,200 ppm by weight.
 6. Themethod of claim 1, wherein the nitrogen-containing dispersant isselected from the group consisting of a polyetheramine; a Mannichreaction product of a hydrocarbyl-substituted phenol, an aldehyde, andan amine; a hydrocarbyl-substituted succinimide; a hydrocarbylamine; andmixtures thereof.
 7. The method of claim 6, wherein the polyetheramineis represented by the formula R[OCH₂CH(R¹)]_(n)A wherein R is ahydrocarbyl group; R¹ is selected from the group consisting of hydrogen,hydrocarbyl groups of 1 to 16 carbon atoms, and mixtures thereof; n is anumber from 2 to about 50; and A is selected from the group consistingof —OCH₂CH₂CH₂NR²R² and —NR³R³ wherein each R² is independently hydrogenor hydrocarbyl and each R³ is independently hydrogen, hydrocarbyl or—[R⁴N(R⁵)]_(p)R⁶ wherein R⁴ is C₂-C₁₀ alkylene, R⁵ and R⁶ areindependently hydrogen or hydrocarbyl, and p is a number from 1-7. 8.The method of claim 7, wherein the hydrocarbyl group R is a C₁-C₃₀ alkylgroup or a C₁-C₃₀ alkyl-substituted phenyl group; R¹ is hydrogen, methylor ethyl; n is a number from about 10 to about 35; and A is—OCH₂CH₂CH₂NH₂.
 9. The method of claim 6, wherein the hydrocarbylsubstituent of the phenol of the Mannich reaction product is derivedfrom a polyisobutylene having a number average molecular weight of from500 to 3,000.
 10. The method of claim 9, wherein the polyisobutylene hasa vinylidene isomer content of at least 70%; and the amine of theMannich reaction product is ethylenediamine.
 11. The method of claim 6,wherein the succinimide is prepared from a hydrocarbyl-substitutedsuccinic acylating agent; and a polyamine wherein the hydrocarbylsubstituent is derived from a polyisobutylene having a number averagemolecular weight of from 500 to 5,000.
 12. The method of claim 6,wherein the hydrocarbylamine is prepared from a chlorinatedpolyisobutylene; and a polyamine wherein the polyisobutylene has anumber average molecular weight of from 500 to 5,000.
 13. The method ofclaim 1, wherein the fluidizer is a polyether represented by the formulaR⁷O[CH₂CH(R⁸)O]_(q)H wherein R⁷ is a hydrocarbyl group; R⁸ is selectedfrom the group consisting of hydrogen, hydrocarbyl groups of 1 to 16carbon atoms, and mixtures thereof; and q is a number from 2 to about50.
 14. The method of claim 13, wherein R⁷ is a C₁-C₃₀ alkyl group or aC₁-C₃₀ alkyl-substituted phenyl group; R⁸ is hydrogen, methyl or ethyl;and q is a number from about 10 to about 35.